On Tue, Jun 20, 2006 at 11:11:15PM -0700, "Hal Finney" wrote:
> I am mostly referring to the philosophical literature on the problems of
> what counts as an instantiation, as well as responses considered here
> and elsewhere.  One online paper is Chalmers' "Does a Rock Implement
> Every Finite-State Automaton?", http://consc.net/papers/rock.html.
> Jacques Mallah (who seems to have disappeared from the net) discussed
> the issue on this list several years ago.
> Now, Chalmers (and Mallah) claimed to have a solution to decide when
> a physical system implements a calculation.  But I don't think they
> work; at least, they admit gray areas.  In fact, I think Mallah came
> up with the same basic idea I am advocating, that there is a degree of
> instantiation and it is based on the Kolmogorov complexity of a program
> that maps between physical states and corresponding computational states.
> For functionalism to work, though, it seems to me that you really need
> to be able to give a yes or no answer to whether something implements a
> given calculation.  Fuzziness will not do, given that changing the system
> may kill a conscious being!  It doesn't make sense to say that someone is
> "sort of" there, at least not in the conventional functionalist view.

If computationalism is true, then a person is instantiated by all
equivalent computations. If you change one instantiation to something
inequivalent, then that instantiation no longer "instantiates" the
person. The person continues to exist, as long as there remain valid
computations somewhere in the universe. And in almost any of the many
worlds variants we consider in this list, that will be true.

> A fertile source of problems for functionalism involves the question
> of whether playbacks of passive recordings of brain states would be
> conscious.  If not (as Chalmers and many others would say, since they
> lack the proper counterfactual behavior), this leads to a machine with a
> dial which controls the percentage of time its elements behave according
> to a passive playback versus behaving according to active computational
> rules.  Now we can turn the knob and have the machine gradually move from
> unconsciousness to full consciousness, without changing its behavior in
> any way as we twiddle the knob.  This invokes Chalmers' "fading qualia"
> paradox and is again fatal for functionalism.

It is only a problem in a single world ontology - in many worlds
ontologies this is not a problem.

> Maudlin's machines, which we have also mentioned on this list from time
> to time, further illustrate the problems in trying to draw a bright line
> between implementations and clever non-implementations of computations.

Indeed  - it points to many worlds ontologies as necessary for
functionalism to be true. This is, in fact, the point of Bruno's main argument.

> In short I view functionalism as being fundamentally broken unless there
> is a much better solution to the implementation question than I am aware
> of.  Therefore we cannot assume a priori that a brain implementation and a
> computational implementation of mental states will be inherently the same.
> And I have argued in fact that they could have different properties.
> Hal Finney
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A/Prof Russell Standish                  Phone 8308 3119 (mobile)
Mathematics                                    0425 253119 (")
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